1. Field of the Invention
The present invention relates to a transporting system provided with transporting vehicles or the like for transporting a transported object, for example, various substrates and the like for manufacturing semiconductor devices, and a method of controlling the transporting system. Here, the “transported object” means a product, an intermediate product, a part, an article, a work, a partly-finished good, a good or the like, or means a box or container for containing such a product or the like, which has been transported or is to be transported by the apparatus.
2. Description of the Related Art
As this type of transporting system, there is a system for transporting a transported object by a plurality of transporting vehicles travelling on a track. The track has, for example, turnout points and junctions, and it is possible to transport the transported object to various positions by the transporting vehicles travelling on the track which diverges in a plurality of directions.
Some transporting systems are provided with a collision avoidance system so that the transporting vehicles do not collide with each other at the junction. For example, Japanese Patent Application Laying Open NO. Hei 10-301626 and Japanese Patent Application Laying Open NO. 2005-115590 disclose such a technology that a communication line is provided near the junction and the transporting vehicles communicate with each other, to thereby recognize one another and prevent the collision.
Moreover, on the assumption that there is something wrong with the aforementioned communication, there has been also suggested a technology of stopping the travel of the transporting vehicle when the communication is not properly performed. For example, Japanese Patent Application Laying Open NO. 2004-46373 discloses such a technology that a base signal is outputted aside from a signal used for the communication, to thereby detect a communication failure.
However, in the technology disclosed in the Japanese Patent Application Laying Open NO. 2004-46373 described above, an apparatus or the like for outputting the base signal needs to be provided separately in order to detect the communication failure, which causes technical problems of a complex system and an increased cost.